The present invention relates to a transmission used for vehicles operated from a riding posture, such as three-wheeled or four-wheeled buggies, and more particularly, it relates to a variable speed transmission for controlling a variable speed by utilizing oil pressure.
In a vehicle of a related art such as, for example, a four-wheeled buggy as shown in FIG. 1, an engine 10 is arranged in such a way that a crank shaft (output shaft) of the engine extends vertically. Power generated by the engine 10 is transmitted to a transaxle 16 and a working apparatus such as a lawn mower 18 by the medium of V-shaped belts 12 and 14, respectively. A driving axle arrangement (not shown) for controlling a variable speed by utilizing oil pressure is incorporated into the trans-axle 16, and rear wheels 19 are rotatably mounted on both ends of the trans-axle 16.
However, in a variable speed transmission comprising the trans-axle 16 and the V-shaped belt 12 used in the four-wheeled buggy as shown in FIG. 1, since the V-shaped belt 12 is twisted laterally on its way, there is a problem regarding poor durability of the V-shaped belt 12. Further, in the above variable speed transmission, since the engine 10 and the trans-axle 16 are indirectly connected to each other by means of the V-shaped belt 12, the trans-axle 16 cannot be supported floatingly on a chassis of the buggy, due to the fact that if the trans-axle 16 is supported floatingly on the vehicle chassis the V-shaped belt 12 leads to misalignment. Accordingly, in the above variable speed transmission, a so-called "rigid axle" in which the trans-axle 16 is rigidly fixed to the vehicle chassis is inevitably used. Further, in the above variable speed transmission, since a hydro-static transmission is incorporated into the trans-axle 16 independently from the engine, there is a disadvantage that the temperature of the working oil in the hydro-static transmission is increased remarkably.
Further, in relation to such variable speed transmission, a multiple axis trans-axle has been proposed as described in the Japanese Utility Model Laid-Open No. 87324/1984. However, in the multiple axis trans-axle, since the trans-axle has a plurality of axes, the trans-axle itself is of a large size, thereby requiring a large space for accommodating the trans-axle on the vehicle.
An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional variable speed transmission by providing an improved variable speed transmission in which a trans-axle of the transmission can be supported floatingly on a vehicle chassis by constituting the engine and the trans-axle as a unit.